Organic light-emitting device and image display system employing the same

ABSTRACT

An organic light-emitting device and an image display system employing the same are provided. The organic light-emitting device includes: a first substrate; an organic light-emitting pixel structure disposed on a top surface of the first substrate; a second substrate having a bottom surface opposite to the top surface of the first substrate; and an optical functional layer disposed over the organic light-emitting pixel structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of pending U.S. patent application Ser.No. 13/918,241, filed on Jun. 14, 2013 and entitled “Organiclight-emitting device and image display system employing the same”,which claims priority of Taiwan Patent Application No. 101121471, filedon Jun. 15, 2012, the entirety of which is incorporated by referenceherein.

BACKGROUND

1. Technical Field

The present invention relates to an organic light-emitting device and animage display system employing the same, and in particular, relates toan organic light-emitting device with high light extraction efficiencyand an image display system employing the same.

2. Description of the Related Art

Recently, with the development and wide application of electronicproducts, such as mobile phones, PDAs, and notebook computers, there hasbeen increasing demand for flat display elements which consume lesselectric power and occupy less space. Organic light-emitting devices areself-emitting and highly luminous, with wide viewing angles, fastresponse speeds, and simple fabrication methods, making them the bestselection of the next generation flat panel display.

An organic light-emitting device is an LED that uses an organic layer asthe active layer. In recent years, organic light-emitting devices havebeen gradually applied in flat panel displays. One trend in organiclight-emitting device technology is to achieve high luminescentefficiency and long operating lifetimes.

As shown in FIG. 1, a conventional organic light-emitting device 10includes a bottom substrate 12, organic light-emitting pixel structure14 (including sub-pixels 14 a-14 d), a filling layer 16, a spacers 18, ablack matrix 20, a color filter layer 22 (including red, blue, and greencolor filter layers), and a top substrate 24. In the conventionalorganic light-emitting device 10, since the organic light-emitting pixelstructure 14 has a metal electrode (with high reflectivity) serving asan anode, a polarizing film 26 is further formed on the top substrate 24in order to reduce the intensity of reflected light L′ produced from theambient incident light L, enhance the contrast of the image displaysystem, and increase the usefulness for outdoor use.

At the present time, due to the poor transmittance (40-45%) of thepolarizing film, the polarizing film 26 reduces the brightness of lightproduced from the organic light-emitting pixel structure 14 whenshielding the ambient light, thereby reducing the light extractionefficiency and electroluminescent efficiency of the image display system10 simultaneously. Hence, the driving voltage of the image displaysystem 10 is increased for maintaining the brightness, resulting inreduced operating lifetime.

Accordingly, a novel organic light-emitting device having high lightextraction efficiency which overcomes the above difficulties andinconveniences is desired.

SUMMARY

An exemplary embodiment of the disclosure provides a system fordisplaying images including an organic light-emitting device. Theorganic light-emitting device includes: a first substrate; an organiclight-emitting pixel structure disposed on a top surface of the firstsubstrate; a second substrate, having a bottom surface opposite to thetop surface of the first substrate; and an optical functional layerdisposed over the organic light-emitting pixel structure, wherein theoptical functional layer has a transmittance of visible light of morethan 50%, and a transmittance of ultraviolet light of less than 20%.

Another exemplary embodiment of the invention provides an image displaysystem, including: the aforementioned organic light-emitting device; andan input unit coupled to the organic light-emitting device, wherein theinput unit provides input to the organic light-emitting device such thatthe organic light-emitting device displays images.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a schematic cross section of a conventional organiclight-emitting device having a polarizing film.

FIG. 2 is a schematic cross section of an organic light-emitting deviceaccording to an embodiment of the disclosure.

FIG. 3 shows a graph plotting transmittance against wavelength of theoptical functional layer according to an embodiment of the disclosure.

FIGS. 4-13 are schematic cross sections of organic light-emittingdevices according to some embodiments of the disclosure.

FIG. 14 schematically shows an image display system including theorganic light-emitting device according to an embodiment of thedisclosure.

FIGS. 15 and 16 show graphs plotting transmittance against wavelength ofthe optical functional layer according to embodiments of the disclosure.

DETAILED DESCRIPTION

The disclosure provides an organic light-emitting device and an imagedisplay system including the same, wherein the organic light-emittingdevice includes an optical functional layer to substitute for theconventional polarizing film.

Since the optical functional layer has a transmittance of visible lightof more than 50%, the organic light-emitting device can have improvedlight extraction efficiency. Further, since the optical functional layerhas a transmittance of ultraviolet light of less than 20%, the opticalfunctional layer can shield the ultraviolet light of ambient light,resulting in the prevention of degradation, by ultraviolet light, of theorganic material of the organic light-emitting device.

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

As shown in FIG. 2, the organic light-emitting device 100 according toan embodiment of the disclosure has a first substrate 102, wherein thefirst substrate 102 can be a quartz substrate, a glass substrate, aceramic substrate, a plastic substrate, or a substrate having activeelements (such as thin film transistor). A second substrate 114 isopposite to the first substrate 102, and a plurality of black matrix 110alternately disposed on the bottom surface 103 of the second substrate114. Herein, the first substrate 102 can be a carrier substrate, thesecond substrate 114 can be a package substrate, and an organiclight-emitting pixel structure 104 is disposed on the top surface 101 ofthe first substrate 102. A color filter layer 112 is disposed below thebottom surface 103 of the second substrate 114, and a spacer 108 isdisposed between the first substrate 102 and second substrate tomaintain a predetermined distance therebetween. According to anembodiment of the disclosure, the organic light-emitting pixel structure104 can include a red sub-pixel 104 a, a green sub-pixel 104 b, a bluesub-pixel 104 c, and a white sub-pixel 104 d, wherein the red sub-pixel104 a, the green sub-pixel 104 b, and the blue sub-pixel 104 ccorrespond to a red filter layer 112 a, green filter layer 112 b, and ablue filter layer 112 c for converting the white light produced from thered sub-pixel 104 a, the green sub-pixel 104 b, and the blue sub-pixel104 c respectively to red, green, and blue lights via the color filterlayer 112. A filling layer 106 is disposed between the organiclight-emitting pixel structure 104 and the color filter layer 112. Itshould be noted that a patterned optical functional layer 116 isdisposed on the filling layer 106 over the white sub-pixel 104 d tocorrespond to the white sub-pixel 104 d, as shown in FIG. 2. The opticalfunctional layer 116 of the disclosure can be a photoresist-like organicmaterial (free of inorganic particles), such as photoresist materialhaving vinylamine groups. The optical functional layer 116 has atransmittance of visible light (400-700 nm) of more than 50% (such as ofbetween 50-70%, 50-80%, or 50-90%) for improving the light extractionefficiency of the organic light-emitting device. Further, the opticalfunctional layer has a transmittance of ultraviolet light (230-400 nm)of less than 20% (such as less than 15%, or less than 10%) forpreventing degradation, by ultraviolet light of the ambient light, ofthe organic material of the organic light-emitting device. For example,according to an embodiment of the disclosure, the method for forming theoptical functional layer 116 includes the following steps. First, acomposition (manufactured and sold by Echem Solutions Co, Ltd, (ECSC)with trade no. CT-9200, including a compound (represented by

wherein R is H, or alkyl group) dissolved in an organic solvent) iscoated on a substrate and then patterned. FIG. 3 shows a graph plottingtransmittance against wavelength (of the visible light) of the opticalfunctional layer 116 of the disclosure. In comparison with thepolarizing film of the conventional organic light-emitting device, theoptical functional layer 116 of the disclosure has a highertransmittance of visible light, since the optical functional layer 116reduces the intensity of ambient light by means of absorption ratherthan polarization.

Further, due to the higher transmittance, the optical functional layer116 improves the light extraction efficiency of the organiclight-emitting device. Moreover, since the optical functional layer ofthe disclosure is made completely of organic material (without inorganicparticles), the optical functional layer can be further patterned viaphotographic exposure and development processes, thereby beingselectively formed on the specific sub-pixels. For example, as shown inFIG. 2, the patterned optical functional layer 116 can be disposed overthe white sub-pixel 104 d. Particularly, the optical functional layer116 can be coplanar with the color filter layer 112, for reducing theinterference of the ambient light. In the conventional organiclight-emitting device, the polarizing film 26 covers all of the surfaceon the top substrate 24, and the light emitted by the red, blue andgreen sub-pixels has to pass through the polarizing film 26, resultingin a reduction in electroluminescent efficiency. In the disclosure,since the optical functional layer 116 can be further patterned and onlydisposed on the white sub-pixel 104 d, the light emitted by the red,blue and green sub-pixel 104 a-c does not pass through the opticalfunctional layer 116, thereby enhancing the contrast of the organiclight-emitting device. The optical functional layer 116 of thedisclosure can have a thickness which keeps the transmittance of visiblelight to more than 50%. For example, the optical functional layer 116has a thickness of between 100 nm-10 μm.

According to another embodiment of the disclosure, as shown in FIG. 4,the organic light-emitting device 100 can include a continuous opticalfunctional layer 116 (i.e. a non-patterned optical functional layer)disposed between the color filter layer 112 and the filling layer 106,wherein a planarization layer 118 disposed on the bottom surface 103 ofthe second substrate 114, and the planarization layer 118 and the colorfilter layer 112 are coplanar in order to facilitate the formation ofthe optical functional layer 116. Further, as shown in FIG. 5, since theoptical functional layer 116 is made completely of an organic material,the optical functional layer 116 can be formed on the color filter layer112 by coating, filling the gap between the color filter layers 112.Therefore, the formation of the planarization layer can be omitted.Moreover, according to another embodiment of the disclosure, the opticalfunctional layer 116 can not only be applied in the RGBW organiclight-emitting device but also a RGB organic light-emitting device 100,as shown in FIG. 6.

It should be noted that, when the RGBW organic light-emitting device 100employs a continuous optical functional layer 116, the organiclight-emitting device 100 can have a higher transmittance of red, green,or blue light, resulting in the organic light-emitting pixel structure104 to emit a light close to the standard white color temperature.

For example, if the organic light-emitting pixel structure 104 emits awhite light with a relatively low intensity of red visible wavelength,an optical functional layer having a relatively high transmittance inthe red visible wavelength would be employed by the organiclight-emitting device to achieve standard white emission. If the organiclight-emitting pixel structure 104 emits a white light with a relativelylow intensity of green visible wavelength, an optical functional layerhaving a relatively high transmittance in the green visible wavelength(as shown in FIG. 15) would be employed by the organic light-emittingdevice to achieve standard white emission; and if the organiclight-emitting pixel structure 104 emits a white light with a relativelylow intensity of blue visible wavelength, an optical functional layerhaving a relatively high transmittance in the blue visible wavelength(as shown in FIG. 16) would be employed by the organic light-emittingdevice to achieve standard white emission. Therefore, the color shiftproblem of the organic light-emitting pixel structure 104 can be solvedby means of the organic light-emitting pixel structure 104 of thedisclosure.

According to another embodiment of the disclosure, as shown in FIG. 7,the continuous optical functional layer 116 can be disposed between thebottom surface 103 of the second substrate 114 and the color filterlayer 112, thereby preventing the alteration of the distance between theorganic light-emitting pixel structure 104 and the color filter layer112. As a result, the viewing angle of design rule can be maintained,and the light leakage can be prevented. According to other embodiments,the continuous optical functional layer 116 disposed between the bottomsurface 103 of the second substrate 114 and the color filter layer 112can be also applied in the RGB organic light-emitting device 100, asshown in FIG. 8.

According to some embodiments of the disclosure, the continuous opticalfunctional layer 116 can be disposed on the top surface 105 of thesecond substrate 114. Namely, the continuous optical functional layer116 can be formed on the outside of the space between the firstsubstrate 102 and second substrate 114, as shown in FIG. 9. The opticalfunctional layer 116 can be formed in advance, and then be bonded on thetop surface 105 of the second substrate 114 via an adhesive layer.Further, the optical functional layer 116 can be formed on the topsurface 105 of the second substrate 114 by coating. Therefore, theprocess complexity of the organic light-emitting device 100 can bereduced.

According to another embodiment of the disclosure, the continuousoptical functional layer 116 formed on the second substrate 114 can alsobe applied in a RGB organic light-emitting device 100, as shown in FIG.10.

According to another embodiment of the disclosure, the organiclight-emitting device 100 can further include a touch-sensitive layer120 in combination with the optical functional layer 116, therebyachieving touch control function, as shown in FIG. 11. Thetouch-sensitive layer 120 can be a patterned transparent conductivelayer. The accompanying drawings show the touch-sensitive layer 120 in aplain rectangle in order to simplify the illustration.

According to some embodiments of the disclosure, the touch-sensitivelayer 120 can be formed on a third substrate 122, and then the opticalfunctional layer 116 can be formed on the optical functional layer,wherein the touch-sensitive layer 120, the third substrate 122, and theoptical functional layer 116 comprise a touch panel 124. Next, the touchpanel 124 can be bonded on the top surface 105 of the second substrate114 via an adhesive layer 126, obtaining an organic light-emittingdevice 100 with touch control function, as shown in FIG. 12. Further,the touch panel 124 can be bonded with the second substrate 114 by meansof the optical functional layer 116 serving as an adhesive layer, asshown in FIG. 13. Particularly, the composition for forming the opticalfunctional layer 116 can further include an adhesive agent forincreasing the adhesivity thereof

As shown in FIG. 14, an image display system 200 including the organiclight-emitting device 100 according to an embodiment of the disclosureis shown. The image display system 200 can be an electric device such asnotebook computer, mobile phone, digital camera, personal data assistant(PDA), desktop computer, television, car display, or portable DVDplayer. The image display system 200 of the disclosure includes theorganic light-emitting device 100 and an input unit 150 coupled to theorganic light-emitting device 100. The input unit 150 is operative toprovide input to the organic light-emitting device 100, such that theorganic light-emitting device 100 displays images.

Accordingly, the organic light-emitting device of the disclosurereplaces the polarizing film with the optical functional layer. Sincethe optical functional layer has a transmittance of visible light ofmore than 50%, the light extraction efficiency of the organiclight-emitting device is enhanced. Further, the optical functional layerhas a transmittance of ultraviolet light of less than 20%, therebypreventing the organic light-emitting device from degradation due toambient light. Moreover, since the optical functional layer of thedisclosure can be made completely of organic material, the opticalfunctional layer can be patterned via photographic exposure anddevelopment processes, improving the contrast of the organiclight-emitting device. Moreover, when the continuous optical functionallayer 116 is applied in the RGBW organic light-emitting device 100, theorganic light-emitting device can emit a light more close to thestandard white color temperature by means of the optical functionallayer having a relatively high transmittance in a specific wavelengthrange (such red visible wavelength, green visible wavelength, or bluevisible wavelength).

While the disclosure has been described by way of example and in termsof the preferred embodiments, it is to be understood that the disclosureis not limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. An organic light-emitting device, comprising: afirst substrate; an organic light-emitting pixel structure disposed on atop surface of the first substrate; a second substrate, having a bottomsurface opposite to the top surface of the first substrate; and anoptical functional layer disposed over the organic light-emitting pixelstructure, wherein the optical functional layer has a transmittance ofvisible light between 50-70%, and a transmittance of ultraviolet lightof less than 20%.
 2. The organic light-emitting device as claimed inclaim 1, further comprising a color filter layer disposed between theorganic light-emitting pixel structure and the second substrate.
 3. Theorganic light-emitting device as claimed in claim 2, further comprisinga filling layer disposed between the organic light-emitting pixelstructure and the color filter layer.
 4. The organic light-emittingdevice as claimed in claim 3, wherein the optical functional layer isdisposed between the color filter layer and the filling layer.
 5. Theorganic light-emitting device as claimed in claim 2, wherein the opticalfunctional layer is disposed between the color filter layer and thebottom surface of the second substrate.
 6. The organic light-emittingdevice as claimed in claim 2, wherein the optical functional layer isdisposed on the color filter layer and the bottom surface of the secondsubstrate.
 7. The organic light-emitting device as claimed in claim 2,wherein the optical functional layer is disposed over the top surface ofthe second substrate.
 8. The organic light-emitting device as claimed inclaim 7, further comprising a touch-sensitive layer, disposed betweenthe optical functional layer and the second substrate.
 9. The organiclight-emitting device as claimed in claim 7, further comprising a thirdsubstrate and a touch-sensitive layer, wherein the third substrate, thetouch-sensitive layer, and the optical functional layer comprise a touchpanel.
 10. The organic light-emitting device as claimed in claim 9,wherein the touch panel is bonded on the top surface of the secondsubstrate via an adhesive layer.
 11. The organic light-emitting deviceas claimed in claim 9, wherein the touch panel is bonded on the topsurface of the second substrate via the optical functional layer.
 12. Animage display system, comprising: the organic light-emitting device asclaimed in claim 1; and an input unit coupled to the organiclight-emitting device, wherein the input unit provides input to theorganic light-emitting device such that the liquid crystal displaydisplays images.
 13. The image display system as claimed in claim 12,wherein the image display system is a mobile phone, digital camera,personal digital assistant, notebook computer, desktop computer,television, car display or portable DVD player.